High-voltage pancake-type coil



May 29, 1923. 1,456,937

A, SCHNEEBERGER HIGH VOLTAGE PANCAKE TYPE COIL Filed June 13. 1917 Patented May 29, 1923.

UNITED" STATES v 1,456,937 PATENT OFFICE.

. C ALFRED sormnnnnnonn, or TURTLE onnnx, PENNSYLVANIA, AssmNoR To INGHOUSE nnnornrc a MANurAorUmNo'coMrANY, A CORPORATION or PENN- sYLv NrA.

HIGH-VOLTAGE PANCAKE-TYPE COIL.

and State of Penns lvania, have invented a new and useful mprovement in High- Voltage Pancake-Type Coils, of which the following is a specification.

My invention relates to current-carrying coils that are adapted for high-voltage service and it has special relation to coils of this character that are to be employed in hi h-voltage power transformers.

' T'Iore particularly, my invention relates to 15 coils of the pancake type that are usually employed in shell-type transformers and, consequently may be subjected to high-voltage strains, such as are occasioned when highfrequency charges or lightning disturbances i .10 impinge upon the end turns of the transformerwwindings.

By means of the present invention, shelltype transformers or those employing pancake coils of the usual form may be advan- 2 tageously employed in high-voltage installations where it is required that'the apparatus, which is to be exposed to all kinds of line disturbances, shall be subjected to unusually severe voltage tests before being 30 placed in service. Because of the mechanical advantages inherent in shell-type transformers or those in which pancake-type coils are employed, such transformers are very desirable in installations where it is essential to offer uninterrupted service.

.Heretofore, the problem of insulatin pancake-type coils has somewhat hamper their use in transformers that are required to undergo unusual severe insulation tests before being installed in service. The coil of the present invention has demonstrated, however, that shell-type transformers, or others employing coils of similar construction, may undergo severe insulation tests without being injured. As a conse uence, transformers embodying the desirab e mechanical features that result from the use of pancake-type coils may be employed under the most severe service conditions.

For a better understanding of the nature and scope of my invention, reference may be had tothe following description and the accompanying drawing in which Figure 1 is a plan view of a current-carrying coil embodying a form of my invention, and Fig.

2 is an enlarged cross-sectional view taken along the line II-II of Fig. 1.

Referring to the drawing, a substantially rectangular sheet or plate 1, having roundedcorners and composed of suitable insulatmg material, such as micarta, has a spiral passageway or groove 2 formed therein. The passageway 2 extends from the outer edge of the plate 1 to a central opening 8 and comprises a plurality of spaced convolutlons, A current-carrying conductor 4 is entwined around the outer edge of the plate 1 and received in the spirally formed groove 2-, substantially as shown. One terminal 5 of the coil 4 extends from the outer edge of the plate 1 and the other terminal 6 extends from the periphery of the opening 3.

Twine is employed for lacing the conductor 4 to the outer and inner edges of the plate 1, as well as the adjacent walls of the groove 2. In this manner, the conductor 4 is mechanically supported throughout its entire length. The convolutions of the spiral 2 conform generally to the shape of the plate 1, the conductor 4 being consequently bent on arcs possessing substantially large radii of curvature.

The spacing of the several convolutions of the spiral 2 from one another is dependent upon the voltage tests to which the assembled coil is to be subjected. The coil illustrated was designed to undergo a voltage test of substantially 150,000 volts between turns. It is to be understood that the coil illustrated in Fig. 1 forms the end turns of a transformer winding which will be subjectedto the most severe voltage stresses when the transformer is connected to a high-voltage transmission system.

For a more detailed view of the construction of the coil shown in Fig. 1, attention is directed to the illustration of Fig. 2. The coil is shown as formed of two superposed plates 1. The spiral groove 2 may be conveniently formed by one operation in the plates 1 by means of a band saw. After the plates 1 have been superposed upon one another, the conductor 4 is disposed in the spiral groove and laced therein by means of the twine 7. It will be noted that the twine 7 also extends through both of the plates 1, thus mechanically at- A between adjacent convolutions of the spiral 2 in order to provide means for cooling the coil, as well as relieving the insulating material'from stresses that tend to distort the insulating sheets or plates 1.

While I have shown and described a single form only of my invention, it will be understood that many modifications may be made therein without departingfrom the spirit and scope of the appended claims.

I claim as my invention:

1. A pancake-type current-carrying coil comprising a plate of insulating material having a spiral slot extending therethrough and a winding so disposed in said slot that the opposite edges thereof are exposed on each side of said plate.

2. A pancake-type current-carrying coil comprising a substantially rectangular plate of insulating material having a central opening and having a. spiral slot extending therethrough to provide a passage from the outer edge of the plate to said opening and a conductor laced in said slot.

3. A pancake-type coil comprising a plate of insulating material having a central opening and a spiral groove comprising a plurality of spaced convolutions, a continuous conductor disposed in said groove, and means for binding said conductor to opposite Walls of said groove in order that said conductor may be mechanically supported of the insulating material throughout its length and may be readily removed from said groove.

4. A pancake-type coil comprising a substantially rectangular plate of insulatin material having rounded corners, .a centra opening and a spiral oove formed therein, sai groove consistlng of a plurality of substantiall tions exten ing from the outer edge of said plate to said central opening, and a conductor disposed in said oove' the width tween said convolutions being materially greater than the thickness of said conductor, whereby abnormally high voltage may be impressed upon said 0011.

5. The method of forming an insulated coil which comprises cutting a plate of insulating material into spiral form and thereafter positioning a conductor between the convolutions thereof.

6. The method of forming an insulated coil which comprises shapin a plate of insulating material into spir form and positioning a conductor brtween the convolutions thereof and lacing said conductor thereto.

In testimony whereof, I have hereunto subscribed my name this 31st day of May, 191

ALFRED SCHNEEBERGER.

rectangular spaced convolu-' 

